Multiple-string insulator suspension



Nav. 6, 1928. 1,690,989.

R. H. MARVIN MULTIPLE STRING INSULATOR SUSPENSION Filed May 24, 1926 INVENTOR.

- RICHHRO H. mHRVIn A TZ'ORNEYS.

the stress is ,Patented Nov. 6, 1928. I

2.10am 11. mm, or near LIVERPOOL, 0111c, ass ronon 1, 0, 89 o-FFic a;

TO mm: B, arrow PATENT,

SONS COMPANY, OF EAST LIVERPOOL, OHIO, A CORPORATION OF-OEIO. 1.

' "M LTIPL -straws msuna'ron sus ension.

' Application flledlay 24,

My invention relates to multiple string insulator suspension units for electric power lines. The object of my inventionis to provide a multiple string suspensionunit in v I which the mechanical'stresses are evenly di vided between the several strings of the suspension unit. I

- In the accompanying drawings- Fi 1 is a side elevation of a suspension 10 unit in which my invention is embodied in one form;

gig. 2 is a similar view of a modification; an

Fig. 3 is a plan view of the latter. With the increasing lengths of span between adjacent towers or poles employed for the support of the cables of electric power lines, the problem of providing insulator strings of mechanical strength adequate for to the heavy mechanical stresses occasioned by the long spans, has become acute. Multiple strings arranged in parallel have been employed in some instances,but in order'to dis-' tribute the stresses evenly between the sev- 35 eral stringsjit has been necessary to employ strings ofexact uniformity in over-all length. This is difiicult to attain in practice by reason of variations both in insulators and in their fittings. To meet this situation, adjustable connections have been utilized, by which the length of the strings has been e ualized. This not only involves the expense adjustment,but is not satisfactory since dependable accuracy is not attained by the workmen, and, as moreover, even after proper adjustment the take-up is apt to vary under service-conditions, with resultant inequality of stresses on the several strings of the suspension unit.

My invention provides a suspension which 40 insures exactdistribution of stresses between the several, strin s regardless of the inescapable slight variations in length incident to manufacture. Moreover the layout is such that in case of failure of one of the'strings, equalized between the remaining strings. Y My invention may be embodied in structures which difi'er in detail while still accomplishing the same result in accordance with the principle which underlies my invention. The structures shown in the accompanying drawings are therefore to be regarded as merely illustrative of the invention. In the form shown in Fig. 1 the suspension unit comprises a pair of hangers 15 and 16,

1926. semi 110 111318.

to the supporting tower (not shown) and the hanger 16- having a link 18 for connection to" a cable clamp or the like (not shown). Uniting the hangers and 16 isa groupof insulator strings 19, eight in number, the several strings being identified by the references a, I), c, d, e, f, g, h. Balance levers 20,21, 22, 23, 24', 25, 26 are eentrally pivoted at a: respectively on arms 27 28, 29, 30, ,31, 32, 33.- Arms 28, 30 and 32 are carried by the hanger 15 and staggered with relation to the arms 27 29, 31 and 33 carried by the hanger 16. Arms 34 and 35 at opposite ends of the hanger 15 support the upper ends of the terminal strings a and k of the series. Links 36 unite,

the several insulator strings at one end to the arms 34 and 35, or to the ends of the several balance levers 21,23. and 25. Links 37 con nect the opposite ends of the strings to the several balance levers 20,22, 24 and 26.

By reason of the fact that the intercon-Q nection between adjacent strings is effected through the staggered balance levers 20- 26, the arrangement afl'ords in effect affie tible system such that by the working of the lev ers inequalities in string length are neutralized' and the stresses of the load are distributed throughout the series of strings with absolute uniformity. Moreover, should one string fail, the portion of the load reviously,

taken by this string is automatica 1y apportioned between the remaining strings, so that the latter are placed under uniform stress at increased load. For example, should string (I fail, the several balance levers 20-26 will tilt. on their. axes until the load is equalized between strings a,b,c,e,f,g,h,'i'ust as. would bethe case were string 03 initial y of such length that levers 2223 were tilted to their extreme limit of oscillation at the moment of load equalization. In the case of failure of string d, the suspension com riseslnot two dead ends 3435, but four ead ends, viz., 22-34 for one group of strings a, b, c, and 23-35 for the other group of strin s e, f, g, h. The load, instead of being ta en by eight strings, is taken by seven, but the tin load is uniformly distributed on the several llu form of four-armed brackets the several arms 40 of the bracket 38- being'sta gered arms in with respect to the arms 4101 the brac et 39. Preferably each arm is provided with a .clevis 42 lying in a plane at right anglesto the plane of the-arm and adapted to receive a pivot pin 43 upon which is pivoted a rock;

lever 44.- To the ends of the rock levers the 1 insulator strings are connected after the same fashion as in the construction first described and with the same efiect. In this layout one of the rockerarms is held against oscillation by stops S to maintain all of the strain axis of the suspension.. The several levers'are arranged at'an angle to each other. in staggered sequence, and are symmetrically", arranged around the axis of sus nsion.

In efi'ect the arran mentjof igs. 2and-3 nding of the hangers; 1' 15 and 16 of Fig.' 1 into circular form; the-, cross arm brackets afi'ord merely a more 'ex- 'mn iecting said hangers, adjacent strings be-. a

is equivalent to the pedient manufacturing proposition. s 1

Various modifications of details ofvcoli-j structionand arrangement of parts will readily occur to those dealing with the problem;

without departing from what I claim as my invention. w

Ic1aim'-, 1. A multiple string suspension insulator unit comprising a pair of spaced hangers, a

.series of balance levers pivoted on the respective hangers, the axes of the levers on one hanger being staggered with respect to the axes of the levers'on the other hanger,

in" combination with a series of insulatorstrings connecting said hangers, adjacent strings being connected at one end-to the opposite ends of a lever pivoted on one hanger,

' while the other ends of said strings are connoted to adjacent levers pivoted on the other hanger, to aflorda flexible ipterconnection between the several stringso rative toeven- 1y distribute between the sai strings the meplanes substantially normal to thechanical stresses upon the group; 2. A multiple string suspension insulator unit comprising apair of spaced hangers. a

series of balance-levers pivoted on the respec- 'tive hangers andarranged at an angle to.

each other in staggered sequence, in combination with a series of insulator strings conmeeting said hangers, adjacent strings bein connected atone end to the opposite ends 0 a lever p voted on onehanger, while" the other are connected to adjaends 0 said strin cent levers pivot on the other hanger, to

afford a flexible interconnection between the severalstrings operative to evenly distribute between the said, strings the mechanical stresses im sed upon the group.

3. A mu tip'le string suspension insulator unit com Using a pair of spaced hangers, a

seriesof alance levers pivoted on the respective hangers and arranged at an angle- ;to each other in staggered sequence and sym: metricall around the axis of suspension, in

combinatlon with a series of insulator strings ing connected at one end to the opposite ends of a lever pivoted on one hanger, while the other ends of said strings'are connected to adjacent levers ivoted on the other hanger,

tribute between t e said strings the mechanical stresses imposed upon theigroup 4. A multiple string suspension insulator unit comprising a pair of mialti-arm hanger members having a common suspension axis,

the arms of the respective hanger members be-' ing staggered, with relation to each other, together with balance levers carried by said arms and insulator strings extending between the balance levers of the respective hanger members and interconnecting the levers in sequence. I

In testimony whereof I have signed my name to this specification;

RICHARD H. MARVIN. 

